This invention concerns the field of electrical signal transmission via a serial telemetry link and to the reconstruction of such transmitted data to original analog and digital forms in an economical manner.
The testing of multi-warhead and dispensed munition delivery systems presents a unique need to send data from many warheads to a single receiving station. Many tested items (e.g., warheads) need to transmit their data sets simultaneously to the ground station not only at the moment of their group release, but also at the instant they are dispersed toward their individual target or targets. With the use of conventional methods, multiple transmitter - receiver - decommutator equipment lines, one transmitter - receiver - decommutator equipment line for each test item and frequency are needed to accommodate such data sets. Using Direct Sequence Spread Spectrum (DSSS) modulation and Code Division Multiple Access (DCMA) techniques however, many test signals can occupy one wider frequency channel. The greatest advantage thereby achieved, is the economy of a single frequency receiver - demodulator - decoder equipment line combination at the ground station.
In using such an arrangement as a framework for the present invention the programmable code transmitters allowing each digital bit stream to be extracted from the single frequency channel are obtained from a commercial vendor in subminiature form (a form which comprises transmitters, but not decoders) and such programmable code transmitters are not therefore part of this invention. In using such a telemetry arrangement however the ground station decoder output is where the single equipment line economy stops because there are as many data streams emerging at this point in the ground station as there are transmitter input test items. This invention recognizes a unique necessary attribute of the transmitter commutation order and architecture used by one, and indeed probably necessarily used by any possible transmitter arrangement, in achieving a decoder allowing a dramatic simplification and economy in the way the many data streams are decommutated into digital byte representations and reconstructed into final forms at the ground station. The final signal form may be the same as the test item transmitter or analog converted for convenience. This invention simplifies the consolidates the decommutation of many transmitter data streams, in effect, continuing the single equipment line cost advantages of Code Division Multiple Access and Direct Sequence Spread Spectrum technology.
The receiver-end processing of telemetry data has also received commercial integrated circuit attention as is for example suggested by the two issued U.S. patents of H. L. Shaw, i.e. U.S. Pat. Nos. 5,016,005 and 5,227,783. The systems described in these and other examples of prior art telemetry systems have progressed significantly in the direction of flexibility and capability to accommodate plural communication functions. The invention described herein is believed however to add a significant additional degree of simplification and optimization to telemetry receiver-end processing. Moreover this simplification and optimization is believed applicable to data links other than those involved with missile and munitions testing and could for example be useful in vehicle and medical communication endeavors both with and without radio frequency linkage equipment.
Electrical apparatus which is commercially available at the time of preparing the present patent document is therefore known to be capable of decommutating serial telemetry data signals into an original parallel digital data format or an analog data format at the receiver end of the telemetry link.
Equipment for transmitter encoding, received signal decoding / and for signal identification for example has been made by Harris Corp. of Melbourne, Fla. Also general purpose decommutator circuits and signal reconstruction hardware circuit arrays, organized by one or two data streams, are available from Berg Systems of Carlsbad, Calif. and Veda Systems of California, Md. These general purpose decommutators have great flexibility and require telemetry frame specifications to be transferred into the decommutator circuit cards by computer. (For examples, the Berg 4411 card is a single decommutator, the 4417 card an 8 channel Digital to Analog signal reconstructor.) The present invention however replaces hardware and software of these types. The present invention is also advantageous in that it requires no telemetry frame specification other than the synchronization or synch word pattern. The architecture of the transmitter, defines each two byte sequence in a way that allows the present invention to cause singular recognition of the synch word without knowing frame length. The desirable end result is the ability to immediately decommutate and reconstruct or convert many digital data streams from the provided decoder with minimal hardware and no support computers. According to an advantage of the invention therefore no specifications are necessary for differing frame lengths.
The concepts of the present invention are therefore disclosed herein in terms of a specific radio frequency link telemetry transmitter and its communication protocol, i.e., in terms of the transmitter provided since at least the early 1990's by Harris Corporation under the name of "Subminiature Telemetry Transmitter SMT0001". The characteristics of this particular telemetry transmitter and indeed other specific influences including for example the telemetry protocol adopted by certain weapons testing facilities (such as the United States Air Force Eglin Air Force Base weapons test range) dictate specific details of the invention disclosed in this document. It is believed that modification of the disclosed apparatus into other forms is within the capability of persons of ordinary skill in the electronic and telemetry arts and therefore within the scope of the present document.
The present invention is believed useful in testing multiple warhead weapons where the simultaneous transmission from diverging warheads could be to a single receptor. Non weapons telemetry uses of the invention are also contemplated, uses such as in hospital/medical and industrial environments. In a hospital for example, need arises to communicate a plurality of vital signs medical data signals from one or several patients to a central point for monitoring or examination. The invention could also be used to send a real time multi-lingual translation on one channel, with the translations to be sorted at a remote location by a single receiver-decoded in accordance with the present invention.